Electrical switch

ABSTRACT

An electrical switch, preferably a small or miniature switch, with a double toggle, with at least one stationary pivot, two fixed contacts, one movable contact and a movable actuating member, wherein a plurality of single toggles are nested one inside the other, so that each member is simultaneously a component of at least two individual toggles, means for providing that the condition &#39;&#39;&#39;&#39;contact pressure zero&#39;&#39;&#39;&#39; is not possible as a permanent condition at the fixed contacts.

United States Patent [191 Leibundgut Feb. 26, 1974 ELECTRICAL SWITCH2,688,058 8/1954 Perrens 200/67 D [75] lnventor: Hans Ulrich Leibundgut,Gasel,

Switzerland Primary Examiner-David Smith, Jr. [73] Assignee: Saia AG,Murten Fribourg Canton, Attorney, g or Firmlmirie and Smiley Switzerland[22] Filed: Oct. 17, 1972 [2i] App]. No.: 298,232 [571 ABSTRACT Anelectrical switch, preferably a small o r miniature [30] Apphcamm PrmmyDam switch, with a double toggle, with. at least one station- Nov. 8,1971 Switzerland 16l88/71 ary pivot, two fixed contacts, ozne movablecontact v and a movable actuating member, wherein a plurality [52] US.Cl 200/67 D of single toggles are nested one inside the other, so [51Int. Cl. H0lh 13/36 that e ch member is simultaneously a component of at[58] Field of Search 200/67 D least two individual toggles, means forproviding that the condition contact pressure zero is not possible [56]References Cited as a permanent condition at the fixed contacts.

UNITED STATES PATENTS 2,414,778 1/1947 Tratsch 200/67 D 5 Claims, 4Drawing Figures 1 ELECTRICAL SWITCH The present invention concerns anelectrical switch, preferably a small or miniature switch, with a doubletoggle action, having at least one fixed pivot, two fixed contacts and amovable contact, and a movable actuating member.

With such switches having a double toggle action, it is basically amatter of combining two single toggles in one assembly in order toobtain two stable switching positions.

Switches which provide this requirement, are known. For example, a snapswitch is known which comprises a toggle switch provided with anoperating spring attached thereto and driven by means of a plunger and areturn spring. The system, comprising a transmission arm and theoperating spring, is set in motion before the zero point of the contactforce is reached. Another well-known small or miniature switch consistsof a strip of band spring arcuately curved and loaded by an adjustingmember near one clamped end and at the other clamped end having at leastone longitudinally extending tongue, the free end of which bears againstone of the two opposed operating points.

These conventional snap switches, however, have among others, theimportant disadvantage that a switching position may occur, in which thecontact pressure is zero and may remain so, thus reducing the life andaccuracy of operation of the switch.

The object of the present invention is to construct a switch comprisinga double toggle having none of the above disadvantages.

According to the present invention there is provided an electricalswitch comprising a double toggle, with at least one stationary pivot,two fixed contacts, one movable contact and a movable actuating member,wherein a plurality of single toggles are nested one inside the other sothat each member is simultaneously a component of at least twoindividual toggles, with at least two spanning members formed aspressure spring members acting in the same direction to ensure thepositioning of the displaceable contact, all the substantially rigidlinks are pivotably connected together and only stressed in tension sothat the sum on the differential ways of all the single toggles is lessthan the differential way of a single toggle, that the lag way is notfunctionally restricted and that the sum of the spring forces actingonthe movable contact changes its sign during the switching operationbefore the actuating member reaches the point of intersection of theextension of the spanning member disposed between a movable joint and astationary pivot joint and the actuating line so that the conditioncontact pressure zero is not possible as a permanent condition at thefixed contacts.

In order to allow such a double toggle to operate under the bestconditions possible, the rigid connecting members, according to anotherembodiment of the in- .vention, are combined in a lamella.

contact on the fixed stop rather increases than decreases before theswitching operation, so that the condition contact pressure zero" is notpossible as a permanent condition.

By way of example, an embodiment of the present invention is illustratedin the drawings and will be described in greater detail hereinafter.

FIG. 1 shows a schematic view of the present invention,

FIG. 2 shows a diagram of the contact pressure of the double toggle ofthe present invention,

FIG. 3 is a side view of a possible variant, and

FIG. 4 is a plan view of the double toggle shown in FIG. 3.

FIG. 1 shows the schematic design of a switch constructed according tothe present invention wherein, for the sake of greater clarity, theswitch housing, the electrical connections, the components for resettingand the like are omitted. The FIG. 1 shows a fixed pivot 1, two fixedcontacts 2 and 3, a movable contact 4, two auxiliary stops 5 and 6, twojoints 7 and 8 which connect the two rigid links 9 and 10, which areunder tensile load and non-positively but pivotably connected to thespanning members 11 and 12 with their compression springs 13, 14. TheFIG. 1 also shows a actuating line 15 along which an actuating member 16is guided on operation. The axis of symmetry 17 of the double toggle isshown, as also angles a and B and the contact pressure Pk indicated bythe arrow 18.

The mode of operation of the double toggle switch of the presentinvention is explained with reference to the schematic illustration inFIG. 1. If the actuating member 16 is in the position shown, the joint 7and the movable contact 4 bear against the stops 5 and 2 because of thepressure of the two springs 13, 14. At the same time, the link 10 isstressed like the connecting member 9.

When the actuating member 16 is moved towards the axis of symmetry 17,the pressure of the joint 7 continuously decreases because of thedecreasing angle (1, whereas the tension in the connecting member 9increases. During this movement of the actuating member 16, the angle[-3 changes only very slightly, since the joint 7 is only very slightlydisplaced towards the actuating line 15. The torque acting in theanticlockwise direction onto the movable contact 4 remains practicallyconstant, since the force acting through the compression spring 13 onthe joint 8 increases rather than decreases. Hence the contact pressurePk remains practically unchanged in the direction of the arrow 18. Atthe latest when the actuating member 16 is slightly below the point ofintersection 19 of the actuating line 15 with the extension 20 of thespanning member 1 1, the single toggle formed by the member 11 and theconnecting member 9 springs over into its second stable position so thatthe joint 7 rests on the auxiliary stop 6. This switching processproceeds differently in practice since the force component exerted bythe link 10 on the joint 7 must also be considered. With correctdimensioning of the two compression springs 13 and 14, and also with acorrectly selected distance between the stationary pivot l and theactuating line 15, it is quite possible to cause the single togglecomprising the parts 9 and 11, to change over before the actuatingelement 16 reaches the point 19. As already mentioned, this is anessential feature. of the double toggle switch of the present invention.It is obvious that the single toggle formed by the link 10 and thespanning member 12 springs over at the moment the pivot 7 passes theaxis formed by the spring member 12. At the same time, the movablecontact 4 suddenly jumps from the fixed contact 2 over to the fixedcontact 3. A condition of zero contact pressure can thus never occurpermanently since this condition would only be fulfilled if the joint 7remained for a long time in the position in which the link 10 isparallel to the spanning member 13. This is impossible, since thisposition of the joint 7 is unstable and is traversed during thejumping-over of the single toggle 9/1 1. What is essential thereby isthat the contact pressure Pk suddenly changes its sign and acts on themovable contact 4 in a direction opposed to the arrow 18.

FIG. 2 shows a graph of the contact pressure Pk. The contact pressure Pkis shown on the ordinate 21 and the way of the actuating member 16 online 15, on the abscissa 22. According to this diagram, the contactpressure Pk remains at first constant during the movement of theactuating member 16, to then gradually rise somewhat until the point 23is reached where the joint 7 (FIG. 1) intersects the axis of thespanning member 12 (FIG. 1) whereon the pressure suddenly reverses atpoint 24 and intersects the abscissa. After the movable contact 4 isfallen onto the fixed contact 3 (FIG. 1), corresponding to the point 25of the diagram, the contact pressure Pk remains constant againsubstantially independently of the lag of the actuating member 16.

The return operation is effected in similar manner; the contact pressurePk is practically constant again up to the point 26, in order to springback through 27 to 28. The difference way of the double toggle as awhole, which is defined by the distance between the points 24 and 27, isequal to or, if all the parts are correctly designed, less than, forinstance, the difference way of the single toggle formed by 9 and 11. g

A practical embodiment of the double toggle switch of the presentinvention is shown in FIGS. 3 and 4, parts therein corresponding tothose in FIG. 1, having the same reference numerals. The two rigidconnecting members 9 and 10 (FIG. 1) have been combined into an lamella29, but without having lost the individual characteristics. Especiallyjoint 7, the link 9 and the link 10 are unchanged. It should be notedthat the link 9 has been lengthened and its free end 9a is anchored inthe switch housing 30. The actuating member 16 is a plunger, thelongitudinal axis of which corresponds to the actuating line 15. Thefixed pivot 1, on which the two compression springs 13 and 14 aremounted, is disposed on the edge of a carrier 31 anchored in the switchhousing 30. The two joints 7 and 8 are formed by specially shaped partsof the lamella 29 and serve as bearing points for the compressionsprings 13 and 14. The two fixed contacts 2 and 3 are also unchanged, aswell as the movable contact 4. The axis of symmetry 17 corresponds tothat of FIG. 1, as also the auxiliary stops 5 and 6. The form of thelamella 29 and the arrangement of the compression springs 13 and 14 maybe seen more easily from FIG. 4. It shows two recesses 32 and 33 formedin the lamella 29, which allow the positioning of the compressionsprings 13 and 14.

While I have illustrated and described one embodiment of my invention, Ido not wish to restrict the scape of protection thereto but reserve theright to make such modifications and rearrangements as may come into thepurview of the appended claims.

I claim: I

1. An electrical switch comprising a double toggle system including afirst and second toggle interconnected by means of a toggle jointdisplaceable between two opposite end positions, said toggles extendingin substantially opposite directions from said toggle joint, contactmeans displaceable between two opposite end positions and fixed at thefree end of said first toggle, an actuating member, the end oppositesaid toggle joint of the second toggle being suspended for displacementby means of said actuating member in a direction substantiallytransversal to said directions of extension of said toggles, a firstpressure spring disposed between said toggle joint and a fixed point anda second pressure spring disposed between said free end of said firsttoggle and a fixed point respectively, each of said toggles beingsubject to tension stresses by said springs, and said contact meansbeing displaceable in a direction substantially transversal to saiddirections of extension of said toggles, said second toggle beingreversible through an unstable position from one of its said endpositions into the other of its end positions upon displacement of itsend opposite said toggle joint by said actuating member, and said firsttoggle and contact means respectively being suddenly reversible byreversal of said second toggle.

2. A switch according to claim 1, wherein said end positions of saidsecond toggle are defined by abutment of said toggle joint against stopmeans.

3. A switch according to claim 1, wherein said toggles and said togglejoint are formed by substantially rigid portions and at least one byweakened portion respectively of one single leaf spring.

4. A switch according to claim 3, wherein one end of said leaf spring isclamped in the switch casing, the clamped end of said leaf spring beinginterconnected with said second toggle by a weakened portion forming ajoint.

5. An electrical switch comprising a double toggle system including aleaf spring having one end thereof fixed at the switch housing, contactmeans fixed at the free end of said leaf spring, said leaf spring havingtwo weakened portions at a distance from each other and each at adistance from said spring ends, such weakened portions forming flexiblejoints, a spring section between said weakened portion and a springsection between the one weakened portion and said contact meansrespectively, each of said spring sections forming a toggle portion,stop means within reach of said contact means and of said weakenedportion located nearer to the contact means for limiting flexionmovement of the leaf spring in a direction substantially transverse tothe flat extension of said leaf spring, an actuating member mounted fordisplacement in a direction substantially transverse to the flatextension of said leaf spring between said one end of the leaf springand its weakened portion next to this one end, a pressure spring actingbetween a fixed point in said switch housing and said free end of theleaf spring and a pressure spring acting between a fixed point and saidweakened portion nearest to said free end of the leaf spring, each ofsaid toggle portions forming together with one of said pressure springsa toggle system of which the one is operable by said actuating memberwhile the other including said contact means is operable by said onetoggle system.

1. An electrical switch comprising a double toggle system including a first and second toggle interconnected by means of a toggle joint displaceable between two opposite end positions, said toggles extending in substantially opposite directions from said toggle joint, contact means displaceable between two opposite end positions and fixed at the free end of said first toggle, an actuating member, the end opposite said toggle joint of the second toggle being suspended for displacement by means of said actuating member in a direction substantially transversal to said directions of extension of said toggles, a first pressure spring disposed between said toggle joint and a fixed point and a second pressure spring disposed between said free end of said first togglE and a fixed point respectively, each of said toggles being subject to tension stresses by said springs, and said contact means being displaceable in a direction substantially transversal to said directions of extension of said toggles, said second toggle being reversible through an unstable position from one of its said end positions into the other of its end positions upon displacement of its end opposite said toggle joint by said actuating member, and said first toggle and contact means respectively being suddenly reversible by reversal of said second toggle.
 2. A switch according to claim 1, wherein said end positions of said second toggle are defined by abutment of said toggle joint against stop means.
 3. A switch according to claim 1, wherein said toggles and said toggle joint are formed by substantially rigid portions and at least one by weakened portion respectively of one single leaf spring.
 4. A switch according to claim 3, wherein one end of said leaf spring is clamped in the switch casing, the clamped end of said leaf spring being interconnected with said second toggle by a weakened portion forming a joint.
 5. An electrical switch comprising a double toggle system including a leaf spring having one end thereof fixed at the switch housing, contact means fixed at the free end of said leaf spring, said leaf spring having two weakened portions at a distance from each other and each at a distance from said spring ends, such weakened portions forming flexible joints, a spring section between said weakened portion and a spring section between the one weakened portion and said contact means respectively, each of said spring sections forming a toggle portion, stop means within reach of said contact means and of said weakened portion located nearer to the contact means for limiting flexion movement of the leaf spring in a direction substantially transverse to the flat extension of said leaf spring, an actuating member mounted for displacement in a direction substantially transverse to the flat extension of said leaf spring between said one end of the leaf spring and its weakened portion next to this one end, a pressure spring acting between a fixed point in said switch housing and said free end of the leaf spring and a pressure spring acting between a fixed point and said weakened portion nearest to said free end of the leaf spring, each of said toggle portions forming together with one of said pressure springs a toggle system of which the one is operable by said actuating member while the other including said contact means is operable by said one toggle system. 